MUC 1 is a transmembrane cell surface mucin best known for its upregulation in breast cancer. The PI observes that its expression correlates with goblet cell differentiation in hamster tracheal epithelial cells in vitro. His preliminary promoter analysis of the hamster Muc 1 gene cloned in his lab reveals the presence of a silencer (P-NRE) not previously described. He proposes conventional methods to (1) deduce the nucleotides comprising the silencer, (2) identify the protein binding to the silencer, (3) clone this protein and (4) perform studies to determine if and how the protein-DNA interaction mediates Muc 1 upregulation during goblet cell differentiation in vitro.